2005 BF225 can't pass 4200 rpm

Just bought a boat with twin BF225. Before I put her into the water, I have a mechanic went through them and replaced the following items:

New batteries
Parker fuel water separators
Low pressure fuel filters
VST filters
HP fuel pump at the starboard motor
full clean up the VST on starboard motor
New spark plugs
Clean the fuel tank vents

Those are my first 4 stroke engines, so I don't know if this is normal or not. It would take 7 to 8 crank to get those motor started when cold. Hot start is easier.

Mu biggest problem is both engine won't go over 4200 rpm under load. I have checked the IAB valves and they seemed to move freely. There is no faulty code, no MIL light, and the engines run smoothly from Idle to 4200 rpm and can stay @ 4200 rpm for hours. The throttle cable on the starboard motor travels a bit less than the one on the port side, both side have some slacks but I don't think it is the root of the problem. This boat has independent fuel system for each motor, and I just put 80 gal of fresh fuel on each side. The motors did not sound like starving, no surging at all.

I am wondering how can I tell if these engines have service bulletin #56 done? I notice that, after a long cruise and then pulling into idle, I can see steam coming out briefly from the the exhaust pipe on the port engine, but not on the starboard side. Does this mean there is water intrusion on the port side?


Sorry for the long post and appreciate any comment and suggestion.

Thanks.

The motors should start on the first turn of key (second turn at the most). Your throttle should be in neutral and not advanced.

If that is what you are doing, then try to put it in throttle only and advance the throttle about 1/4 throttle. Try starting and see what happens. Be ready to pull the throttle back, so engine does not overrev.

If it starts right away with the throttle advanced, then you have an issue with the Idle Air Control.

When you start, the IAC allows more air to enter the combustion chamber and once started the idle will be somewhat high....then the idle lowers slowly to normal idle. Once the engine is warmed up, it closes down a lot and does not need to work so hard at start up, once the engine has been running.

What does your mechanic say about the low rpms?

Are you trimming the motors up once you are on plane?

Do you have trim tabs on the motor that may be down all the way and creating drag....until you raise them up...once on plane?

What boat do you have?

What are the size (diameter and pitch)? Maybe it is not propped correctly. Again...what is the opinion of your mechanic (who has had a very close relationship with your motor).

Final question.....are you actually getting full throttle. To check, you would have to put the throttles at full throttle and check the throttle body arm on the top rear of each motor. There is a slot in the arm and the roller should be close (if not at) the top of end of the opening. If not, then the mechanic has some adjusting to do.

It is possible that the ETEC is not kicking in, however, it seems unlikely for it to be happening on both engines.

Once more last one.....are the motors mounted at the proper level? Again...a question for the mechanic to check.

Just a few thoughts of things that could be causing the problem. Others will probably have additional thoughts.

Mike

Thank you Mike for the detailed reply!

Frist, I will see if advancing throttle will help starting the motor. Will a bad IAC limit the WOT?

My boat is KingCat 296, the normal load is around 10,000 to 11,000 LB. The props come with the boat are PowerTech 4 blade 15-1/4”x19”. I think she is 3 steps over propped; the previous owner did this intentionally for high speed trolling for Wahoo. The boat can plane at 15mph under 2,500 rpm. I have discussed with a prop expert, he suggested 3x15-1/2”x17”, but he also think the motors should do better than 4,200 rpm even with current props.

Sadly to say that boaters at the northeast need to beg for an appointment with good marinas/mechanics. The boat needed some minor electrical works, along with reinstalling the hardtop, but no one wanted to do the work so the boat was sat since last Sept. Two mechanics agreed to work on my boat this spring but cancelled the very last minutes. In earlier July, through a good friend, I finally found a mechanic who is not a certified Honda mechanic but has good reputation. The goal is to get the boat in the water since half of the boating season was gone already, and then we will deal with issues along the way. He first found the starboard side, HP fuel pump was bad, and after replacing it he found the “fuel pressure regulator” is not working correctly. He took the VST out, cleaned it and fixed the problem. He measured both motors’ fuel pressure right at 45 psi and started the engine without a problem. So we launched the boat from his riverfront shop where is about 30 mins to the ocean. At first the tachometers were all over the place, reading 1,000/1,500 rpm at idle, 4,500/5,000 rpm at WOT. My mechanic was not willing to past 30 knots in the river and had no time to test her in the ocean, so we don’t know the actual WOT rpm/speed at that time. After that I just drove her back to my slip, which is 30 mile north. I ran between 25 and 30 knots for most of the trip. A week later I followed the Honda manual to reset the switches on the tachos, and then I learned the motors are stuck at 4,200rpm, fully trimmed at 30 knots. I can see the cavitation plate at planning, but I do think the motors can be raised another hole since I can trim the motor a long way up. This is my first cat so I am still learning the optimal trim angle.

I did find there are plays on the throttle cable. On the starboard side, there is about ¾” distance between the roller and the end of the arm. Does the roller need to reach the end of the L-shape opening on the black colored arm? The port side is better but the roller is still not in the leg of the L-shape. I have printed out CHawk-man’s instruction of throttle cable adjustment. I will try that the coming weekend.

Another thing I found was that, after slowing down to idle from 25+ knots; the fuel bulb is a little soft, unlike my previous 2 strok motor, its bulb is always hard after first of the day. Is this normal? The fuel lines before the bulbs are original, but from my uneducated point of view, they look at bit thin and soft.

Last question, I could see a little steam coming out of the exhaust hole, only for a few second after I slowed her down from cruise speed. Does this mean I have the exhaust pipes corrosion problem as shown in SB #56?

Thanks again for the help. I would like to see what I can do before giving up and sending her to Honda dealer that might cost me another week or two from boating……

In addition to all of the good advice from Hondadude, one simple question - are you pumping the primer bulbs until they are firm before attempting to start?

Well, another simple question - are the primer bulbs oriented so that the inflow side is lower than the out flow side? They should be - that assures that the check valve in the primer bulb can work properly. BTW - the primer bulb will be a "little" soft while running. It does not stay completely hard at all.

You might call Honda Customer Service at 770-497-6400 to see if they have any record of SB #56 being performed on those engines. Have your model and serial number for each engine ready.

From what you described in your last post, I do suspect that your throttle cables are in need of adjustment.

chawk_man said:

In addition to all of the good advice from Hondadude, one simple question - are you pumping the primer bulbs until they are firm before attempting to start?

Well, another simple question - are the primer bulbs oriented so that the inflow side is lower than the out flow side? They should be - that assures that the check valve in the primer bulb can work properly. BTW - the primer bulb will be a "little" soft while running. It does not stay completely hard at all.

You might call Honda Customer Service at 770-497-6400 to see if they have any record of SB #56 being performed on those engines. Have your model and serial number for each engine ready.

From what you described in your last post, I do suspect that your throttle cables are in need of adjustment.

Click to expand...

Thank you Chawk. I have read tons of threads/replies from you and Mike in the past three weeks, and tried to trouble shooting steps by steps. You guys rock!

Yes and yes, I did pump the bulbs before the first start of the day; And the bulbs are alined correctly. The arrow points up. My boat has two fuel tanks and two Racor s3213, each s3213 connects to a crossover valve in case one tank is empty/water intrusion. My question is that the fuel lines between the crossover valve and primer bulbs look comparatively narrow and soft (versus other fuel lines external）. Probably 3/8" in outter diameter and I can pinch it to stop the flow. However, by the look of the fittings and clamps, they look like a factory rigging job. Is this normal? I am considering replacing all the fuel lines and wondering if this will help.
One of my slip neighbor is a mechanic, he told me that Racor is no good because the seal between the filter and the clear bowl will leak over time and let air goes into the fuel line. I have been using Racor clear bowl for years and never heard about this. Can air in fuel line be the issue?
Thanks,
Vince

Yes, air in the fuel line COULD be your issue. BUT, if it is happening with both motors, that would be odd. To eliminate that possibility, why not just clamp off the fuel lines going to the crossover valve as they come out of each Racor, then test.

However, I would advise to clear up the throttle cable and throttle arm adjustments first.

I would also try to contact other owners of the KingCat 296 or similar dual hull boats with 200's or 225's mounted and see how they are propped. I know that there have been discussions on The Hull Truth forum about Worldcat's. I do suspect that you are over propped, but have no experience with dual hull boats.

I've got a similar issue. My mechanic buddy, very familiar with big Hondas, says one last thing to check is the vtec solenoid. I haven't done it yet.

Other than that, is does sound like a combination of throttle cable adjustment and propping. My props are 15.5 x 15 on a 29' mono @ 11,300 loaded.

Thanks!
My plan is to fix the throttle cable first, if not thing changed, I would work on the fuel lines.
I would definitely check into the VTEC solenoid, however, the odds for for both motor having the same problem is low. The common parts for both motors are the props,fuel line between crossover valve, and control binnacle (had reconnected the binnacle in July, it's a bit hard to find neutral on both side). If nothing works, I will find a prop shop to borrow a set of props for testing.
I did PM some KingCat owner on THT, person who replied me owns different brand of motor. I will keep trying. Thank you all for the suggestions.
Vince

Well, I'm not that familiar with the VTEC system, but it seems to me that if the VTEC is not kicking in, then you have the same thing as a BF 200 (which does not have the VTEC.) So if that were the problem, it should lack the power you are used to, but still get up into the higher RPM's without much problem.

To the best of my understanding, the VTEC kicks in at about 4500 rpm. It switches off at 4300 rpm. When the engine is operating at below 4500 rpm, the two intake valves are operated independently by the two overhead cams. When the VTEC kicks in it opens a solenoid which applies hydraulic pressure to small hydraulic pistons in a third rocker arm, locking the intake valves together and giving them higher lift, allowing more air into the combustion chambers. I may have that all wrong, but that's what I read somewhere back in the cobwebs of my mind.

I think we would all be open to a more detailed and accurate explanation of the VTEC system and how it really works.

Wow, that's very detailed explanation. I will go through the basics first to see if I can at least get to 4,500rpm.
Vince

Just got a response, another KingCat owner with BF225s uses 4x15x15". So, there are 800 rpm right there, and once the VTEC kicked in, I probably can get 5,500 rpm. However, there are not much gain on the top end speed and efficiency, according to the other owner, his boat is doing high 30mph at WOT and between 1.5~2 mpg cruising between 20 and 30 mph, which is what I get now. The plus side is reduce the stress on these motors.

"......his boat is doing high 30mph at WOT". That doesn't sound right.

Again, my boat loaded is 11,300lbs. And your cat should be faster than my mono. I know of 3 other exact same boats as mine with various 225's on them, including Hondas. They all WOT at 45-47mph.

Is your cat planing (like World Cat) or displacement (like Glacier Bay)?

btravlin2 said:

"......his boat is doing high 30mph at WOT". That doesn't sound right.

Again, my boat loaded is 11,300lbs. And your cat should be faster than my mono. I know of 3 other exact same boats as mine with various 225's on them, including Hondas. They all WOT at 45-47mph.

Is your cat planing (like World Cat) or displacement (like Glacier Bay)?

Click to expand...

Well, I am new to Cat so I can't tell you how this boat compared to a mono regarding speed or efficiency. Only thing I know the ride is very different, going from 0 to 30 knots seems effortless, but then she just stops there and leaves me puzzled.
My boat is a planning cat but with very sharp deadrise at the stern (25 degree, no pad, asymmetric hull), so she is not a speed demon. There is a WorldCat 266 with twin BF200 in the shop of my marina, the bottom of the WorldCat is not a V-hull, it is rounded with a pad at the stern, probably that's what they call "semi-displacement" hull.
One of the reasons I did not jump to 15" props is that, after consulting PropGod at THT and using the Prop Slip Calculator from Mercury Racing site, four-blade 15" prop will probably max out 42 mph at 6,000 rpm. So, with bottom paint and fully loaded, 37~38 mph WOT seems reasonable. PropGod recommend 3x15-1/2x17 for both bite and top speed. That's another $900 for props. So, it will be my last thing to try.

I agree with btravlin - you should get much better performance from dual 225's at WOT than 38 mph, especially on a CAT.

And just as a judgement call, I would think you will get better performance overall if you are slightly under-propped, rather than slightly over-propped.


FYI - There are a lot of used props in good condition on eBay. Take a look there before buying new ones. I don't know where you are located, but even if you get a marginal prop at a really good price, all of the marine shops in this area have contacts with machine shops that refurbish props at reasonable prices and they seem to do a good job.

chawk_man said:

I agree with btravlin - you should get much better performance from dual 225's at WOT than 38 mph, especially on a CAT.

And just as a judgement call, I would think you will get better performance overall if you are slightly under-propped, rather than slightly over-propped.


FYI - There are a lot of used props in good condition on eBay. Take a look there before buying new ones. I don't know where you are located, but even if you get a marginal prop at a really good price, all of the marine shops in this area have contacts with machine shops that refurbish props at reasonable prices and they seem to do a good job.

Click to expand...

I am not disagreeing with you and btravlin about the top speed of this hill. I know for fact that she is a 50mph boat with Suzuki 250. I was just saying that, the other owner propped his boat, for his specific reason, with 4 blade 15" pitch props. With that specific props, his boat should hit 42mph at the rev limit, and the number dropped in real world condition. I too would like to see more top end so I am looking at 3 blade 17" pitch props. Already contacted two private sellers, after I going through throttle adjustment this weekends, and then will try to loan a pair of 17" to see if things improved.
Is there any other thing I am missing? clogged injectors? bad coils? ECM problems?

Thanks- Vince

BTW, I followed CHawk's suggestion calling Honda customer service line. I gave my series number to the rep and he told me that he "did not see the notation of SB#56" on my engines, instead, he saw "SB#70- upgrade to new O2 sensor". Does this mean my engines have #56 done?

If you have SB #56, check your SN's against those on page 1. If you don't have a copy, send me an email at [email protected]. Having SB #70 performed does not mean that SB #56 has been performed. The only way to tell for sure is to get to the exhaust tubes and compare the ones on your engine to the pictures in SB #56.

SB #70 just replaces the original HO2 sensor for BAGJ-1000001 ~ 1309999 and BAHJ-1000001 ~ 1309999. This old style HO2 sensor has the 22 mm hex head fitting.

But for SN's BAGJ-1400001 ~ 1509999 and BAHJ-1400001 ~ 1509999 it replaces the ECM and installs an upgraded HO2 sensor. This new sensor fits in an adapter and has a 14 mm hex head fitting.

So it's easy to tell whether they simply replaced the original HO2 sensor, or installed an upgraded sensor. If you got the upgraded ECM, you will see a sticker on it with the part number 34750-ZY3-A04.

Would injectirs be an issue? My buddy runs Yams, he gets his replaced at least once a year. Sends them back for cleaning, flow testing and inspecting. He loses 400 rpm from top end and knows it's time.

I would think if your friend ran a maintenance dose of RingFree he wouldn't have to do that.

I mostly agree with btravalin. I have almost 1900 hours on my 2007 BF 225 and no indication of injector problems. However, I do dose the fuel with Yamalube Ring Free (1 oz per 10 gallons of fuel) twice a year because I troll a lot. Remember that his is basically a Honda J35A3 auto engine and when placed in auto's hardly ever needs injector cleaning. The marine environment is certainly different, but it's a really solid engine.

4 bladed props. As those you are running and mainly mentioning here create better hole shot as in they are great for water skiing and so on where as good old 3 bladed will ( sometimes drastically ) improve top end speed and bring WOT RPM up. I dear say you have explored this avenue but thought I would put it out there in case of any over sight.

Updates

Thanks for all the replies. Spent three days on th water and here are some updates.
First, I adjusted my throttle cables to remove the slack, big thanks to Chawk-man. Now the rollers on the throttle body reach almost the end of control arms. This along gave me 400+ more rpm! Now my starboard techometer shows at least 4,600 rpm. The port side techometer is having some issues. At first, it went up as the starboard side did, but after hitting 4,500, it suddenly fluctuated between 3000 and 4500, and then went to zero. It went back to normal after I pulled the throttle back to idle. But it would never went over 4400 afterward. The port engine had a new alternator this spring. I am wondering if this has something to do with the alternator, the belt, or maybe a grounding issue?

I added one bottle of SeaFoam to each fuel tank, checked the IAC valves (the port side is bit tight). Now the starboard engine starts much easier and I can see the starboard side IAC works properly, it raises the idle rpm to 1200 at cold start. The port side still need 5 to 6 cranks to start, no change when I advance the throttle. One thing I noticed is that, the new batteries my mechanic put in are rated 1000 MCA, Honda requires minimum 800 CCA. Can this be a problem?

I checked the engine height, the cavitation plates are 1" above the bottom of the hull, but I can barely see them at planning. I discussed with two mechanics about raising the motors but both of them told me not to do it. They said my boat is a big heavy fishing boat with a lot of weight at the bow, the current motor height works just find and provides the leverage to push up the bow. One mechanic even told me to cover th vent holes on the props. He said vent hold is for increasing rpm for top speed, covering the vent holes would give me better bite at mid-range. I got a nice pair of Mirage Plus 17p props from him, but could not find hub kits anywhere near my marina.. So need to wait for another week to see the results.

Thanks again for everyone's help.

Keep us posted.

Updates:

For the last four weeks, we either had bad weather, very crowded in the bay or had lots of guests boating with us. It's really hard to test new props with 12 people on board and 6 out of them sitting at the bow. But I kind of found that these engines worked hard to pass 4500 ~ 4600 rpm with Mirage Plus 15.5"x 17". I cleaned all of the air passages really good, checked/tightened all the clamps on the fuel lines, sprayed a lot of WD-40 on the IACs to make sure they move freely. Finally yesterday morning the wind and current were minimal and only my family were on board, so I opened up the throttle and saw rpm passed 4800 rpm on the starboard side, the tachometer on the port side still showed zero after passing 4500 rpm. I trimmed up as much as I could and saw the starboard motor reached 5,400 rpm running close to 36 knots according to my GPS and then I hit heavy traffic again. Changing props definitely helps but I don't know if other things I have done that help too. So far I am happy with the performance.
Now questions: I replaced a new alternator on the port engine in July, and yesterday I found the alternator belt is a bit loosen up now. Does this relates to the tachometer malfunctioning?
Also, coming from an old 2-stoke, I often have to check these BF225s for peeing to make sure they are idling. However I kind of felt the motors were louder at idle after running above 4000 rpm for 30 minutes or longer. Does this make sense at all?

Big tanks to everyone for your help in sorting out my problems.

Tighten belt on alternator,might answer your own question,#2 NO

TDL,
I was doing a google search and found your post.
I have the exact boat you have with 225 hondas. I purchased mine this summer, also. I will check to see what props I am running when I get home this evening.
My boat with a heavy load will run 41 mph @ 5500 rpms.
My engines are mounted one hole from the lowest possible position and I still believe they are too high. I am moving them to the lowest setting and checking results this weekend.

Thanks rrbgt44,
The boating season is almost over in my area, probably will go out two more times and then she will go into winter storage. Then I will have more time to check with fuel lines, VST screens and other problems. Now I have one tachometer stops at 4,200 rpm, and both trim gauges are not working that seemed to work fine early this season. One mechanic blamed my motor issues on the Racor filter, he said he had seen too many failures on the seal between the metal filter and the clear bowl that leaked air. However, I have Racor for years and never have a problem.
Why do you think the motor is too high? My motors are mounted the same place as yours, and I have checked with other owners that their Hondas seems to be mounted at the same height. I am still learning how to drive this Cat. It's very different than any mono hull I had before; this boat does not have bow rise when coming onto plane, and I can trim the motors way up until the props bark but the hull never porpoises. So I am actually thinking about raise the motor to increase the WOT rpm. However I have never run her with full tanks/fish boxes/livewell, but constantly with 10+ passengers on board and lots of water toys. I estimate the weight is between 10,000lb and 10,500lb. Also, I normally run her with front, center piece up for ventilation, and side curtains, this might cause me some mph as well but my current WOT is close to what you have seen at heavy load.
Keep me updated on your test!

I'm lowering the motors because I am trying to get it run with the bow higher. As it is, the motors lose their bite before I can get the bow up.
I owned a 26 twin vee that loved to ride bow high and a buddies 33 world cat is the same. I'm thinking the boat will ride better and might even pick up a little speed, if i can raise the bow a little.
My top speed was with 5 people, full of fuel, water and supplies for a Bahamas run. I have a huge top that slows me down considerably, but have no bottom paint. I would think your top speed should be equal or even a little better than mine.

rrbgt44 what props are you running?

I have 3 blade stainless solas props 15 1/4 x 17.

Here is a photo to show how high my engines are mounted. I prefer they be a little high to a little low, but this seems extreme. I only have one inch left and I'm bottomed out, so I hope it's enough.

Was your motor fully trimmed in when you took the picture?